Ammoxidation catalyst for use in producing acrylonitrile or methacrylonitrile from propane or isobutane by ammoxidation

ABSTRACT

An ammoxidation catalyst comprising a compound oxide of Mo, V, Nb, and at least one element selected from the group consisting of Te and Sb, wherein the compound catalyst exhibits an X-ray diffraction pattern satisfying the following relationship: 
     
         0.40≦R≦0.75 
    
     wherein R represents the intensity ratio defined by the following formula: 
     
         R=P.sub.1 /(P.sub.1 +P.sub.2) 
    
     wherein P 1  and P 2  represent the intensities of peak 1 and peak 2 appearing at diffraction angles (2θ) of 27.3±0.3° and 28.2±0.3°, respectively. 
     By the use of the ammoxidation catalyst of the present invention, not only can acrylonitrile or methacrylonitrile be produced in high yield, but also oxidative decomposition of ammonia feedstock into nitrogen can be effectively suppressed, thereby enabling an improved utilization of ammonia as a feedstock.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ammoxidation catalyst for use inproducing acrylonitrile or methacrylonitrile from propane or isobutaneby ammoxidation in the gaseous phase. More particularly, the presentinvention is concerned with an ammoxidation catalyst comprising acompound oxide which contains specific component elements in specificatomic ratios and which exhibits an X-ray diffraction pattern whereinthe intensities of two peaks respectively appearing at diffractionangles (2θ) of 27.3±0.3° and 28.2±0.3° have a specific relationship toeach other. By the use of the ammoxidation catalyst of the presentinvention, not only can acrylonitrile or methacrylonitrile be producedin high yield, but also oxidative decomposition of ammonia feedstockinto nitrogen can be effectively suppressed, thereby enabling animproved utilization of ammonia as a feedstock. The present invention isalso concerned with a process for producing acrylonitrile ormethacrylonitrile by using such an excellent ammoxidation catalyst.

2. Prior Art

There has been a well-known process for producing acrylonitrile ormethacrylonitrile by ammoxidation of propylene or isobutylene. Recently,as a substitute for such a process using propylene or isobutylene,attention has been attracted to a process for producing acrylonitrile ormethacrylonitrile by gaseous phase catalytic ammoxidation of propane orisobutane, i.e., by gaseous phase catalytic reaction of propane orisobutane with ammonia and molecular oxygen. Further, a number ofproposals have been made with respect to catalysts for use in theammoxidation of propane or isobutane.

For example, as a catalyst for use in producing acrylonitrile ormethacrylonitrile by ammoxidation of propane or isobutane, oxidecatalysts containing molybdenum, vanadium, niobium and tellurium areknown. Such oxide catalysts are disclosed in U.S. Pat. No. 5,049,692,U.S. Pat. No. 5,231,214, U.S. Pat. No. 5,281,745, U.S. Pat. No.5,422,328, Unexamined Japanese Patent Application Laid-OpenSpecification No. 6-227819, Unexamined Japanese Patent ApplicationLaid-Open Specification No. 7-144132, Unexamined Japanese PatentApplication Laid-Open Specification No. 7-232071, Unexamined JapanesePatent Application Laid-Open Specification No. 8-57319 and UnexaminedJapanese Patent Application Laid-Open Specification No. 8-141401.

Further, oxide catalysts containing molybdenum, vanadium, antimony andniobium are disclosed in European Patent Application Publication No. 767164 A1 and Unexamined Japanese Patent Application Laid-OpenSpecification No. 5-213848.

In addition, oxide catalysts containing vanadium and antimony aredisclosed in U.S. Pat. No. 4,760,159 and U.S. Pat. No. 4,797,381.

Among the above-mentioned prior art documents, each of U.S. Pat. No.5,281,745 and U.S. Pat. No. 5,422,328 discloses a crystalline metaloxide catalyst exhibiting an X-ray diffraction pattern having peaks atdiffraction angles (2θ) of 22.1±0.3°, 28.2±0.3°, 36.2±0.3°, 45.2±0.3°and 50.0±0.3°, respectively; Unexamined Japanese Patent ApplicationLaid-Open Specification No. 6-227819 discloses a crystalline metal oxidecatalyst exhibiting an X-ray diffraction pattern having peaks atdiffraction angles (2θ) of 22.1±0.5°, 28.2±0.5°, 36.2±0.5°, 45.2±0.5°and 50.0±0.5°, respectively; and Unexamined Japanese Patent ApplicationLaid-Open Specification No. 7-232071 discloses a crystalline metal oxidecatalyst exhibiting an X-ray diffraction pattern having peaks atdiffraction angles (2θ) of 9.0±0.3°, 22.1±0.3°, 27.3±0.3°, 29.2±0.3° and35.4±0.3°, respectively. However, in any of these prior art documents,there is no description about the intensity ratio of peaks appearing atdiffraction angles (2θ) of 27.3±0.3° and 28.2±0.3°, respectively.

The oxide catalysts described in these prior art documents aredisadvantageous in that none of them exhibit a satisfactorily high yieldof acrylonitrile or methacrylonitrile in the ammoxidation of propane orisobutane.

Applied Catalysis A General (vol. 157, pp. 143-172, 1997) describesthat, during the course of the ammoxidation of propane, ammonia, whichis one of the gaseous feedstocks for the ammoxidation is converted notonly to acrylonitrile as a desired product, but also inevitably toby-products, such as acetonitrile and hydrocyanic acid, and, isoxidatively decomposed into nitrogen. The conventional catalysts for usein the ammoxidation of propane or isobutane pose a problem in that,during the ammoxidation, decomposition of ammonia into nitrogen occursto a high extent. Therefore, it is desired to develop an improvedcatalyst having an advantage in that the decomposition of ammonia duringthe ammoxidation can be suppressed, thereby enabling an efficientutilization of the feedstock ammonia for the ammoxidation of propane orisobutane.

On the other hand, U.S. Pat. No. 5,534,650 discloses a method forperforming an ammoxidation of an alkane in which gaseous ammonia is fedinto a reactor from a plurality of ammonia inlets provided therein sothat the fed ammonia is efficiently utilized for the ammoxidationreaction. However, this method is disadvantageous not only in thatextensive operations are required due to the use of complicatedequipment, but also in that a satisfactory effect for suppressing theammonia decomposition cannot be obtained.

SUMMARY OF THE INVENTION

In this situation, the present inventors have conducted extensive andintensive studies with a view toward developing an improved catalyst foruse in producing acrylonitrile or methacrylonitrile from propane orisobutane by ammoxidation in the gaseous phase, which enables theammoxidation in which not only can a high yield of acrylonitrile ormethacrylonitrile be achieved, but also a decomposition of feedstockammonia into nitrogen can be effectively suppressed, thereby enabling animproved utilization of feedstock ammonia. As a result, it hasunexpectedly been found that the above objective can be achieved by anammoxidation catalyst comprising a compound oxide which containsspecific component elements in specific atomic ratios and which exhibitsan X-ray diffraction pattern satisfying the following relationship:

    0.40≦R≦0.75

wherein R represents the intensity ratio defined by the followingformula:

    R=P.sub.1 /(P.sub.1 +P.sub.2)

wherein P₁ and P₂ represent the intensities of peak 1 and peak 2appearing at diffraction angles (2θ) of 27.3±0.3° and 28.2±0.3°,respectively.

The present invention has been completed, based on the above novelfinding.

Accordingly, it is an object of the present invention to provide anammoxidation catalyst for use in producing acrylonitrile ormethacrylonitrile from propane or isobutane by ammoxidation in thegaseous phase, which is advantageous not only in that acrylonitrile ormethacrylonitrile can be produced in high yield, but also in that anoxidative decomposition of feedstock ammonia into nitrogen can beeffectively suppressed, thereby enabling an improved utilization offeedstock ammonia.

It is another object of the present invention to provide a process forproducing acrylonitrile or methacrylonitrile from propane or isobutaneby ammoxidation using such an excellent catalyst.

The foregoing and other objects, features and advantages of the presentinvention will be apparent to those skilled in the art from thefollowing detailed description taken in connection with the accompanyingdrawings and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

In the drawings:

FIG. 1 is an X-ray diffraction pattern (hereinafter, frequently referredto simply as "XRD pattern") of the ammoxidation catalyst obtained inExample 1;

FIG. 2, which is an enlarged view of the XRD pattern of FIG. 1 and takenin the range of from about 25° to about 29° in terms of the diffractionangle (2θ), is an explanatory view showing how to obtain the value ofintensity ratio R;

FIG. 3 is an XRD pattern of the ammoxidation catalyst obtained inExample 3;

FIG. 4 is an XRD pattern of the ammoxidation catalyst obtained inComparative Example 1;

FIG. 5 is an XRD pattern of the ammoxidation catalyst obtained inComparative Example 4;

FIG. 6 is an XRD pattern of the ammoxidation catalyst obtained inComparative Example 5;

FIG. 7 is an XRD pattern of the ammoxidation catalyst obtained inExample 11; and

FIG. 8 is an XRD pattern of the ammoxidation catalyst obtained inComparative Example 12.

DESCRIPTION OF REFERENCE NUMERALS

A₁ : Apex of peak 1

A₂ : Apex of peak 2

B₁ : Point at which the curved line of the XRD pattern exhibits aminimum value, as viewed along the intensity axis vertical to the2θ-axis, in the range of 26.4±0.3° in terms of the diffraction angle(2θ)

B₂ : Point at which the curved line of the XRD pattern exhibits aminimum value, as viewed along the intensity axis vertical to the2θ-axis, in the range of 27.7±0.3° in terms of the diffraction angle(2θ)

B₃ : Point at which the curved line of the XRD pattern exhibits aminimum value, as viewed along the intensity axis vertical to the2θ-axis, in the range of 28.8±0.3° in terms of the diffraction angle(2θ)

C₁ : Point at which a straight line drawn downwardly from peak apex A₁vertically to the 2θ-axis intersects with a straight line connectingpoints B₁ and B₂

C₂ : Point at which a straight line drawn downwardly from peak apex A₂vertically to the 2θ-axis intersects with a straight line connectingpoints B₂ and B₃

DETAILED DESCRIPTION OF THE INVENTION

In one aspect of the present invention, there is provided anammoxidation catalyst for use in producing acrylonitrile ormethacrylonitrile from propane or isobutane by ammoxidation in thegaseous phase, comprising a compound oxide represented by the followingformula (1):

    Mo.sub.0.1 V.sub.p X.sub.q Nb.sub.r Z.sub.s O.sub.n        (1)

wherein:

X is at least one element selected from the group consisting oftellurium and antimony;

Z is at least one element selected from the group consisting oftantalum, tungsten, chromium, titanium, zirconium, bismuth, tin,hafnium, manganese, rhenium, iron, ruthenium, cobalt, rhodium, nickel,palladium, platinum, silver, zinc, boron, aluminum, gallium, indium,germanium, lead, phosphorus, rare earth elements and alkaline earthmetals; and p, q, r, s and n are, respectively, the atomic ratios ofvanadium, X, niobium, Z and oxygen, relative to molybdenum,

wherein

    0.1≦p≦0.6;

    0.01≦q≦0.6;

    0.01≦r≦0.6;

    0≦s≦1;

and

n is a number determined by the valence requirements of the otherelements present,

the compound oxide exhibiting an X-ray diffraction pattern satisfyingthe following relationship (2):

    0.40≦R≦0.75                                  (2)

wherein R represents the intensity ratio defined by the followingformula (3):

    R=P.sub.1 /(P.sub.1 +P.sub.2)                              (3)

wherein P₁ and P₂ represent the intensities of peak 1 and peak 2appearing at diffraction angles (2θ) of 27.3±0.3° and 28.2±0.3°,respectively.

In another aspect of the present invention, there is provided a processfor producing acrylonitrile or methacrylonitrile, which comprisesreacting propane or isobutane with ammonia and molecular oxygen in thegaseous phase in the presence of the catalyst defined above.

For an easy understanding of the present invention, the essentialfeatures and various preferred embodiments of the present invention areenumerated below.

1. An ammoxidation catalyst for use in producing acrylonitrile ormethacrylonitrile from propane or isobutane by ammoxidation in thegaseous phase, comprising a compound oxide represented by the followingformula (1):

    Mo.sub.1.0 V.sub.p X.sub.q Nb.sub.r Z.sub.s O.sub.n        (1)

wherein:

X is at least one element selected from the group consisting oftellurium and antimony;

Z is at least one element selected from the group consisting oftantalum, tungsten, chromium, titanium, zirconium, bismuth, tin,hafnium, manganese, rhenium, iron, ruthenium, cobalt, rhodium, nickel,palladium, platinum, silver, zinc, boron, aluminum, gallium, indium,germanium, lead, phosphorus, rare earth elements and alkaline earthmetals; and p, q, r, s and n are, respectively, the atomic ratios ofvanadium, X, niobium, Z and oxygen, relative to molybdenum,

wherein

    0.1≦p≦0.6;

    0.01≦q≦0.6;

    0.01≦r≦0.6;

    0≦s≦1;

and

n is a number determined by the valence requirements of the otherelements present,

the compound oxide exhibiting an X-ray diffraction pattern satisfyingthe following relationship (2):

    0.40≦R≦0.75                                  (2)

wherein R represents the intensity ratio defined by the followingformula (3):

    R=P.sub.1 /(P.sub.1 +P.sub.2)                              (3)

wherein P₁ and P₂ represent the intensities of peak 1 and peak 2appearing at diffraction angles (2θ) of 27.3±0.3° and 28.2±0.3°,respectively.

2. The catalyst according to item 1 above, wherein R in relationship (2)satisfies the following relationship:

    0.43≦R≦0.70.

3. The catalyst according to item 1 or 2 above, which further comprisesa silica carrier having supported thereon the compound oxide, whereinthe silica carrier is present in an amount of from 20 to 60% by weight,based on the total weight of the compound oxide and the silica carrier.

4. A process for producing acrylonitrile or methacrylonitrile, whichcomprises reacting propane or isobutane with ammonia and molecularoxygen in the gaseous phase in the presence of the catalyst of item 1above.

5. The process according to item 4 above, wherein R in relationship (2)satisfies the following relationship:

    0.43≦R≦0.70.

6. The process according to item 4 or 5 above, wherein the catalystfurther comprises a silica carrier having supported thereon the compoundoxide, wherein the silica carrier is present in an amount of from 20 to60% by weight, based on the total weight of the compound oxide and thesilica carrier.

Hereinbelow, the present invention will be described in more detail.

The ammoxidation catalyst of the present invention has a characteristicfeature in that it comprises a compound oxide represented by thefollowing formula (1):

    Mo.sub.1.0 V.sub.p X.sub.q Nb.sub.r Z.sub.s O.sub.n        (1)

wherein:

X is at least one element selected from the group consisting oftellurium and antimony;

Z is at least one element selected from the group consisting oftantalum, tungsten, chromium, titanium, zirconium, bismuth, tin,hafnium, manganese, rhenium, iron, ruthenium, cobalt, rhodium, nickel,palladium, platinum, silver, zinc, boron, aluminum, gallium, indium,germanium, lead, phosphorus, rare earth elements and alkaline earthmetals; and

p, q, r, s and n are, respectively, the atomic ratios of vanadium, X,niobium, Z and oxygen, relative to molybdenum,

wherein

    0.1≦p≦0.6,

preferably

    0.2≦p≦0.4;

    0.01≦q≦0.6,

preferably

    0.05≦q≦0.3;

    0.01≦r≦0.6,

preferably

    0.03≦r≦0.3;

    0≦s≦1,

preferably

    0≦s≦0.1;

and

n is a number determined by the valence requirements of the otherelements present,

and that the compound oxide exhibits an X-ray diffraction patternsatisfying the following relationship (2):

    0.40≦R≦0.75                                  (2)

wherein R represents the intensity ratio defined by the followingformula (3):

    R=P.sub.1 /(P.sub.1 +P.sub.2)                              (3)

wherein P₁ and P₂ represent the intensities of peak 1 and peak 2appearing at diffraction angles (2θ) of 27.3±0.3° and 28.2±0.3°,respectively.

The XRD analysis of the ammoxidation catalyst of the present inventionis conducted as follows.

In the XRD analysis of the ammoxidation catalyst, diffraction angles(2θ) are measured using Cu--Ka as a source of X-ray. The XRD analysis isconducted under the following conditions:

Tube voltage: 30 kV

Tube current: 40 mA

Divergence slit: 1°

Scatter slit: 1°

Receiving slit: 0.3 mm

Scanning speed: 6°/min.

Sampling interval: 0.02°.

In the XRD pattern obtained by the above-mentioned XRD analysis, theintensity ratio R is obtained as follows.

In the present invention, P₁ and P₂, which are the intensities of peak 1and peak 2 appearing at diffraction angles (2θ) of 27.3±0.3° and28.2±0.3°, respectively, can be obtained as follows. For example, inFIG. 2 hereof, which is an enlarged view of the XRD pattern of FIG. 1(showing an XRD pattern of the ammoxidation catalyst obtained in Example1), there is shown an explanatory view illustrating how to obtain thevalue of intensity ratio R[=P₁ /(P₁ +P₂)]. The explanatory view of FIG.2 is taken in the range of from about 25° to about 29° in terms of thediffraction angle (2θ).

In FIG. 2, characters A₁ and A₂ designate the apexes of peaks 1 and 2appearing at diffraction angles (2θ) of 27.3±0.3° and 28.2±0.3°,respectively. Characters B₁, B₂ and B₃ respectively designate points atwhich the curved line of the XRD pattern exhibits minimum values, asviewed along the intensity axis vertical to the 2θ-axis, in the rangesof 26.4±0.3°, 27.7±0.3° and 28.8±0.3°, respectively, in terms of thediffraction angle (2θ). In the present invention, the term "minimumvalue" used in connection with the curved line of the XRD pattern meansa point at which the gradient of a tangential line of the curved line ata base portion of each of peaks 1 and 2 shifts from negative topositive, or a point at which the gradient converges to zero, whereinthe gradient is taken as viewed in the coordinates of the 2θ-axis andthe intensity axis. Character C₁ designates a point at which a linedrawn downwardly from peak apex A₁ vertically to the 2θ-axis intersectswith a straight line connecting points B₁ and B₂. Character C₂designates a point at which a line drawn downwardly from peak apex A₂vertically to the 2θ-axis intersects with a straight line connectingpoints B₂ and B₃.

The intensity of peak 1 (which is represented by character P₁ in thepresent invention) is defined as the length of straight line segment A₁C₁ which extends from peak apex A₁ (of peak 1) to point C₁ ; and theintensity of peak 2 (which is represented by character P₂ in the presentinvention) is defined as the length of straight line segment A₂ C₂ whichextends from peak apex A₂ (of peak 2) to point C₂.

Briefly stated, referring to FIG. 2 hereof showing an X-ray diffractionpattern taken in the range of from about 25° to about 29° in terms ofthe diffraction angle (2θ), the intensity of peak 1 is defined as thelength of straight line segment A₁ C₁ which extends from peak apex A₁(of peak 1) to point C₁ ; and the intensity of peak 2 is defined as thelength of straight line segment A₂ C₂ which extends from peak apex A₂(of peak 2) to point C₂,

wherein:

the point C₁ is a point at which a line drawn downwardly from peak apexA₁ vertically to the 2θ-axis intersects with a straight line connectingpoints B₁ and B₂,

the point C₂ is a point at which a line drawn downwardly from peak apexA₂ vertically to the 2θ-axis intersects with a straight line connectingpoints B₂ and B₃, and

the points B₁, B₂ and B₃ are, respectively, points at which the curvedline of the X-ray diffraction pattern exhibits minimum values, as viewedalong the intensity axis vertical to the 2θ-axis, in the ranges of26.4±0.3°, 27.7±0.3° and 28.8±0.3°, respectively, in terms of thediffraction angle (2θ).

As mentioned above, in the present invention, the intensity ratio (R) isdefined as the ratio of the intensity of peak 1 to the sum of theintensities of peaks 1 and 2. Therefore, the intensity ratio R isdefined by the following formula (3):

    R=P.sub.1 /(P.sub.1 +P.sub.2)                              (3)

wherein P₁ and P₂ represent the intensities of peak 1 and peak 2,respectively.

In the present invention, it is requisite that the intensity ratio R bein the range of from 0.40 to 0.75. It is preferred that the intensityratio R is in the range of from 0.43 to 0.70, more advantageously from0.50 to 0.69. When the intensity ratio R is less than 0.40 or is morethan 0.75, problems arise in the ammoxidation of propane or isobutaneusing a catalyst exhibiting such a value of the intensity ratio R, notonly in that, an extensive oxidative decomposition of feedstock ammoniaoccurs, but also in that the yield of acrylonitrile or methacrylonitrileis disadvantageously lowered.

The ammoxidation catalyst of the present invention may further comprisea silica carrier having supported thereon the compound oxide. The silicacarrier is preferably present in an amount of from 20 to 60% by weight,more preferably from 20 to 40% by weight, based on the total weight ofthe compound oxide and the silica carrier.

With respect to the source of each component element for theammoxidation catalyst of the present invention, there is no particularlimitation. Representative examples of sources of component elements forthe ammoxidation catalyst of the present invention include ammoniumheptamolybdate [(NH₄)₆ Mo₇ O₂₄.4H₂ O] as a source of molybdenum;ammonium metavanadate (NH₄ VO₃) as a source of vanadium; telluric acid(H₆ TeO₆) as a source of tellurium; antimony trioxide (Sb₂ O₃) as asource of antimony; and niobic acid (Nb₂ O₅.nH₂ O) as a source ofniobium.

Examples of sources of other component elements for the ammoxidationcatalyst of the present invention include nitrates, oxalates, acetates,hydroxides, oxides, ammonium salts and carbonates of elements, such astantalum, tungsten, chromium, titanium, zirconium, bismuth, tin,hafnium, manganese, rhenium, iron, ruthenium, cobalt, rhodium, nickel,palladium, platinum, silver, zinc, boron, aluminum, gallium, indium,germanium, lead, phosphorus, rare earth elements and alkaline earthmetals.

With respect to the source of silica as an optionally employable carrierfor the compound oxide of the ammoxidation catalyst of the presentinvention, a silica sol is preferred. Examples of silica sols include asilica sol stabilized with alkali metal ions and a silica sol stabilizedwith ammonium ions. A silica sol stabilized with ammonium ions ispreferred.

The ammoxidation catalyst of the present invention can be produced by aconventional method. For example, the catalyst can be produced by amethod comprising the steps of (1) preparing a raw material mixture (forexample, a slurry of raw materials), (2) drying the raw material mixtureobtained in step (1) above to obtain a dried catalyst precursor, and (3)subjecting the dried catalyst precursor obtained in step (2) above tocalcination.

Hereinbelow, explanation is made with respect to a preferred embodimentof the above-mentioned method for producing the ammoxidation catalyst ofthe present invention, which comprises steps (1), (2) and (3), above.

In step (1), a raw material mixture is prepared. First, a solution isprepared by dissolving ammonium heptamolybdate, ammonium metavanadateand telluric acid in water (this solution is designated "solution A").Alternatively, when antimony is used as a component element, a solutionis first prepared by a method in which an antimony trioxide powder isdispersed in an aqueous solution of ammonium metavanadate, therebyobtaining a dispersion and the obtained dispersion is heated underreflux conditions to thereby obtain a solution or slurry, and then,ammonium heptamolybdate and, optionally, telluric acid are added to theobtained solution or slurry to obtain a further solution or slurry (thissolution or slurry is designated "solution A'").

On the other hand, oxalic acid and niobic acid are dissolved in water oraqueous ammonia to obtain a solution (this solution is designated"solution B"). With respect to the obtained solution B, it is preferredthat the molar ratio of oxalic acid to niobium is in the range of from 1to 4, more advantageously from 2 to 4. With respect to the obtainedsolution B, it is also preferred that the molar ratio of ammonia toniobium is 2 or less, more advantageously 1 or less.

As mentioned above, the compound oxide of the catalyst of the presentinvention optionally contains at least one component element selectedfrom the group consisting of the following elements: tantalum, tungsten,chromium, titanium, zirconium, bismuth, tin, hafnium, manganese,rhenium, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum,silver, zinc, boron, aluminum, gallium, indium, germanium, lead,phosphorus, rare earth elements and alkaline earth metals. A nitrate, anoxalate, an acetate, a hydroxide, an oxide, an ammonium salt, acarbonate or the like of the above-mentioned at least one componentelement is dissolved in water, to obtain a solution or slurry (thissolution or slurry is designated "solution C").

To solution A or A' are successively added solution B and solution C, tothereby obtain a raw material mixture.

When the ammoxidation catalyst of the present invention furthercomprises a silica carrier having supported thereon the compound oxide,the raw material mixture further contains a silica sol. The addition ofa silica sol can be made at any time during the above preparationoperation for the raw material mixture, which comprises preparingsolution A or A' and solutions B and C and mixing together thesesolution A or A' and solutions B and C.

In step (2), the raw material mixture obtained in step (1) above issubjected to spray drying. The spray drying of the raw material mixturecan be generally conducted by centrifugation, two-phase flow nozzlemethod or high pressure nozzle method to obtain a dried particulatecatalyst precursor. In this instance, it is preferred to use air whichhas been heated by an electric heater, steam or the like, as a heatsource for drying. It is preferred that the temperature of the spraydryer at an entrance to the dryer section thereof is from 150 to 300° C.Spray drying can be performed in an alternative handy way, for example,by spraying the raw material mixture onto a steel plate which has beenheated to a temperature of 100 to 300° C.

In step (3), the dried particulate catalyst precursor obtained in step(2) above is calcined to thereby obtain a catalyst. The driedparticulate catalyst precursor is calcined in an atmosphere of an inertgas, such as nitrogen gas, argon gas or helium gas, which issubstantially free of oxygen, preferably under a flow of an inert gas,at a temperature of 500 to 700° C., preferably 550 to 650° C. for 0.5 to5 hours, preferably 1 to 3 hours.

The oxygen concentration of the inert gas used for the calcination isgenerally 1,000 ppm or less, preferably 100 ppm or less, as measured bymeans of a gas chromatography or a trace oxygen analyzer.

For the calcination, use can be made of a kiln, such as a rotary kiln, atunnel kiln, a muffle kiln and a fluidized firing kiln. The calcinationof the catalyst can be repeatedly conducted.

Prior to and/or after the calcination in step (3), the dried catalystprecursor and/or a catalyst obtained by calcining the dried catalystprecursor may be subjected to pre-calcination or post-calcination. Thatis, prior to the calcination in step (3), the dried catalyst precursorobtained in step (2) above may be pre-calcined in an atmosphere of airor under a flow of air at a temperature of 200 to 350° C. for 10 minutesto 5 hours. Further, after the calcination, the obtained catalyst may besubjected to post-calcination in an atmosphere of air at a temperatureof 200 to 400° C. for 5 minutes to 5 hours.

Further, after the calcination, the obtained catalyst may be subjectedto grinding, and the resultant pulverized oxide catalyst may besubjected to recalcination in an atmosphere of an inert gas, such asnitrogen gas, argon gas or helium gas, which is substantially free ofoxygen, preferably under a flow of an inert gas, at a temperature of 400to 700° C., preferably 500 to 600° C. for 0.5 to 5 hours, preferably 1to 3 hours.

Acrylonitrile or methacrylonitrile can be produced by the process of thepresent invention comprising reacting propane or isobutane with ammoniaand molecular oxygen in the gaseous phase in the presence of thecatalyst of the present invention.

Propane or isobutane and ammonia used in the process of the presentinvention need not be of a very high purity but may be of a commercialgrade.

Examples of sources of molecular oxygen include air, oxygen-rich air,and pure oxygen. Further, such a source of molecular oxygen may bediluted with helium, argon, nitrogen, carbon dioxide, steam or the like.

In the process of the present invention, the molar ratio of ammonia topropane or isobutane used for the ammoxidation may be generally in therange of from 0.1 to 1.5, preferably from 0.2 to 1.2. By the use of thecatalyst of the present invention, the ammoxidation of propane orisobutane can be conducted under conditions wherein the molar ratio ofammonia to propane or isobutane is at a low level, as compared to thelevel required in the case of a process using the conventionalammoxidation catalyst.

The molar ratio of molecular oxygen to propane or isobutane used for theammoxidation may be generally in the range of from 0.2 to 6, preferablyfrom 0.4 to 4.

In the process of the present invention, the ammoxidation temperature isgenerally in the range of from 350 to 600° C., preferably from 380 to470° C.

In the process of the present invention, the ammoxidation pressure isgenerally in the range of from 0.1 to 10 atm., preferably fromatmospheric pressure to 3 atm.

The time of contact (contact time) between the gaseous feedstocks andthe catalyst is generally in the range of from 0.1 to 30 sec·g/cc,preferably from 0.5 to 10 sec·g/cc. In the process of the presentinvention, the contact time during the ammoxidation of propane orisobutane is determined according to the following formula: ##EQU1##

wherein:

W represents the weight (g) of the catalyst contained in the reactor;

F represents the flow rate (cc/min) of the gaseous feedstocks [in termsof the value under the normal temperature and pressure conditions (0°C., 1 atm)];

T represents the ammoxidation temperature (° C.); and

P represents the ammoxidation pressure (atm.).

The process of the present invention for producing acrylonitrile ormethacrylonitrile by ammoxidation of propane or isobutane in the gaseousphase can be conducted in a conventional reactor, such as a fixed-bedreactor, a fluidized-bed reactor or a moving-bed reactor. The reactionmode employed in the process of the present invention may be either aone-pass mode or a recycling mode.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in more detail withreference to the following Examples and Comparative Examples, whichshould not be construed as limiting the scope of the present invention.

In the following Examples and Comparative Examples, the conversion (%)of propane, the selectivity (%) for acrylonitrile, the yield (%) ofacrylonitrile and the ammonia decomposition ratio (%), each used forevaluating the results of the ammoxidation of propane, are defined asfollows: ##EQU2##

EXAMPLE 1

Preparation of an ammoxidation catalyst

An ammoxidation catalyst comprising a compound oxide represented by theformula:

    Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n

was prepared as follows.

39.0 g of ammonium heptamolybdate [(NH₄)₆ Mo₇ O₂₄.4H₂ O], 8.53 g ofammonium metavanadate (NH₄ VO₃) and 11.16 g of telluric acid (H₆ TeO₆)were dissolved in 160 g of water at a temperature of 60° C. whilestirring, followed by cooling to 30° C., to thereby obtain a solution(solution A).

4.25 g of niobic acid (Nb₂ O₅.nH₂ O) (Nb₂ O₅ content: 76.0% by weight)and 8.27 g of oxalic acid (H₂ C₂ O₄.2H₂ O) were dissolved in 50 g ofwater at a temperature of 60° C. while stirring, followed by cooling to30° C., to thereby obtain a solution (solution B). In the obtainedsolution B, the molar ratio of oxalic acid to niobium (hereinafter,frequently referred to as "[H₂ C₂ O₄ :Nb] molar ratio") was 2.7.

Solution B obtained above was added to solution A obtained above and theresultant mixture was stirred for about 30 minutes to obtain a rawmaterial mixture.

The obtained raw material mixture was subjected to spray drying byspraying it onto a Teflon-coated iron plate heated to a temperature of140° C., thereby obtaining a dried particulate catalyst precursor. 25 gof the obtained catalyst precursor was charged into a quartz tube havingan inner diameter of 20 mm, and then calcined at a temperature of 600°C. for 2 hours under a stream of nitrogen gas at a flow rate of 1,000Ncc/min. (Ncc means cc as measured under the normal temperature andpressure conditions, namely at 0° C. under 1 atm.), to thereby obtain acatalyst.

With respect to the oxygen concentration of the nitrogen gas used forthe calcination, measurement was done by means of a trace oxygenanalyzer 306WA (manufactured and sold by Teledyne AnalyticalInstruments, U.S.A.). As a result, it was found that the oxygenconcentration of the nitrogen gas was 1 ppm.

The composition of the catalyst is shown in Table 1 together with thefollowing conditions for the preparation of the catalyst: the [H₂ C₂ O₄:Nb] molar ratio and the [ammonia:Nb] molar ratio in solution B, thedrying method for the raw material mixture, the calcination conditions,and whether or not a grinding of the catalyst was conducted.

X-ray diffractometry

An XRD pattern was obtained with respect to the catalyst obtained above.Specifically, the above obtained catalyst was subjected to measurementby X-ray diffractometry using an X-ray diffractometer RAD-IIIA(manufactured and sold by Rigaku Corporation, Japan) as follows.

Preparation of a sample

About 0.5 g of the catalyst was placed in an agate mortar and subjectedto grinding for 2 minutes by manually operating an agate pestle. Theresultant catalyst powder was subjected to sifting, to thereby obtain apowdery catalyst having a particle size of 53 μm or less. The obtainedpowdery catalyst was placed on a sample-holding table for an XRD patternmeasurement. The table had a rectangular recess in the surface thereof(which has the following dimensions: a length of 20 mm, a width of 16 mmand a depth of 0.2 mm), and the powdery catalyst in the recess waspressed using a stainless steel spatula having a flat shape so that thesurface of the powdery catalyst became flat.

XRD pattern measurement conditions

An XRD pattern measurement was conducted under the following conditions.

    ______________________________________                                        Source of X-ray    Cu-Kα.sub.1 + Cu-Kα.sub.2                      Detector           Scintillation counter                                      Single crystal     Graphite                                                   used for a                                                                    monochromator                                                                 Tube voltage       30 kV                                                      Tube current       40 mA                                                      Divergence slit    1°                                                  Scatter slit       1°                                                  Receiving slit     0.3 mm                                                     Scanning speed     6°/min.                                             Sampling interval  0.02°                                               Scanning method    2θ/θ method                                    ______________________________________                                    

The diffraction angle (2θ) correction was conducted by performing acalibration using X-ray diffractometry data obtained with respect to asilicon powder. As a smoothing treatment, both an 8-point high-frequencyattenuation type smoothing and a 24-point differential type smoothingwere performed. (A high-frequency amplification type smoothing was notperformed.)

The XRD pattern obtained with respect to the catalyst in Example 1 isshown in FIG. 1, and the intensity ratio R determined with respect topeaks 1 and 2 [appearing at diffraction angles (2θ) of 27.3±0.3° and28.2±0.3°, respectively] of the XRD pattern is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, an ammoxidation of propane wasconducted as follows.

0.3 g of the obtained catalyst was charged into a fixed-bed reactiontube having an inner diameter of 4 mm. In the reaction tube containingthe catalyst, an ammoxidation of propane was performed under conditionswherein the flow rate of a gaseous feedstock mixture (i.e., a gaseousmixture of propane, ammonia, molecular oxygen and helium) was 6 Ncc/min,the [propane:ammonia:molecular oxygen:helium] molar ratio in the gaseousfeedstock mixture was 1.0:1.2:3.0:14.8, the ammoxidation temperature was420° C., the ammoxidation pressure was 1 atm., and the contact timebetween the catalyst and the gaseous feedstock mixture was 1.2 sec·g/cc.The produced gaseous reaction mixture was subjected to analysis by meansof an on-line gas chromatography.

The results of the evaluation of the above ammoxidation are shown inTable 3.

EXAMPLE 2

Preparation of an ammoxidation catalyst

2.0 g of the catalyst obtained in Example 1 above was charged into aquartz tube having an inner diameter of 20 mm, and then subjected to are-calcination at 550° C. for 2 hours under a stream of nitrogen gas ata flow rate of 200 Ncc/min., to thereby obtain a catalyst. Thecomposition of the catalyst and the conditions for the preparation ofthe catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

EXAMPLE 3

Preparation of an ammoxidation catalyst

2.0 g of the catalyst obtained in Example 1 above was placed in anautomatic agate mortar and subjected to grinding for 40 minutes. 1.5 gof the resultant powder was charged into a quartz tube having an innerdiameter of 20 mm, and then subjected to a re-calcination at 550° C. for2 hours under a stream of nitrogen gas at a flow rate of 200 Ncc/min.,to thereby obtain a catalyst. The composition of the catalyst and theconditions for the preparation of the catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained XRDpattern is shown in FIG. 3, and the intensity ratio R is shown in Table1.

Ammoxidation of propane

Substantially the same ammoxidation of propane as in Example 1 wasrepeated except that the catalyst obtained above was used (instead ofthe catalyst obtained in Example 1), that the flow rate of the gaseousfeedstock mixture was 10 Ncc/min. (instead of 6 Ncc/min.) that thecontact time was 0.5 sec·g/cc (instead of 1.2 sec-g/cc). The results ofthe evaluation of the above ammoxidation are shown in Table 3.

EXAMPLE 4

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example 3except that the re-calcination was conducted for 1 hour (instead of 2hours). The composition of the catalyst and the conditions for thepreparation of the catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 3 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

EXAMPLE 5

Preparation of an ammoxidation catalyst

An ammoxidation catalyst comprising a compound oxide represented by theformula:

    Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n

was prepared as follows.

78.0 g of ammonium heptamolybdate [(NH₄)₆ Mo₇ O₂₄.4H₂ O], 17.06 g ofammonium metavanadate (NH₄ VO₃) and 22.3 g of telluric acid (H₆ TeO₆)were dissolved in 350 g of water at a temperature of 70° C. whilestirring, followed by cooling to 30° C., to thereby obtain a solution(solution A).

8.5 g of niobic acid (Nb₂ O₅.nH₂ O) (Nb₂ O₅ content: 76.0% by weight)and 16.6 g of oxalic acid (H₂ C₂ O₄.2H₂ O) were dissolved in 110 g ofwater at a temperature of 60° C. while stirring, followed by cooling to30° C., to thereby obtain a solution (solution B). In the obtainedsolution B, the [H₂ C₂ O₄ :Nb] molar ratio was 2.8.

Solution B obtained above was added to solution A obtained above and theresultant mixture was stirred for about 30 minutes to obtain a rawmaterial mixture.

The obtained raw material mixture was subjected to spray drying byspraying it onto a Teflon-coated iron plate heated to a temperature of140° C., thereby obtaining a dried particulate catalyst precursor.

Then, substantially the same calcination operation as in Example 1 wasconducted except that 3 g of the catalyst precursor obtained above wasused (instead of 25 g of the catalyst precursor obtained in Example 1),and that the flow rate of nitrogen gas was 330 Ncc/min. (instead of1,000 Ncc/min.), to thereby obtain a catalyst. The composition of thecatalyst and the conditions for the preparation of the catalyst areshown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

EXAMPLE 6

Preparation of an ammoxidation catalyst

An ammoxidation catalyst comprising a compound oxide catalystrepresented by the formula:

    Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n

was prepared as follows.

39.0 g of ammonium heptamolybdate [(NH₄)₆ Mo₇ O₂₄.4H₂ O], 8.53 g ofammonium metavanadate (NH₄ VO₃) and 11.16 g of telluric acid (H₆ TeO₆)were dissolved in 160 g of water at a temperature of 60° C. whilestirring, followed by cooling to 30° C., to thereby obtain a solution(solution A).

4.25 g of niobic acid (Nb₂ O₅.nH₂ O) (Nb₂ O₅ content: 76.0% by weight)and 7.04 g of oxalic acid (H₂ C₂ O₄.2H₂ O) were dissolved in 50 g ofwater at a temperature of 60° C. while stirring, followed by cooling to30° C., to thereby obtain a solution (solution B). In the obtainedsolution B, the [H₂ C₂ O₄ :Nb] molar ratio was 3.0.

Solution B obtained above was added to solution A obtained above and theresultant mixture was stirred for about 30 minutes to obtain a rawmaterial mixture.

The obtained raw material mixture was subjected to spray drying byspraying it onto a Teflon-coated iron plate heated to a temperature of140° C., thereby obtaining a dried particulate catalyst precursor.

Then, 10 g of the catalyst precursor obtained above was calcined insubstantially the same manner as in Example 1, to thereby obtain acatalyst. The composition of the catalyst and the conditions for thepreparation of the catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

EXAMPLE 7

Preparation of an ammoxidation catalyst

1.0 g of the catalyst obtained in Example 6 above was placed in aporcelain dish and subjected to post-calcination at 320° C. for 0.3 hourin an atmosphere of air, thereby obtaining a catalyst. The compositionof the catalyst and the conditions for the preparation of the catalystare shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

EXAMPLE 8

Preparation of an ammoxidation catalyst

1.0 g of the catalyst obtained in Example 6 above was placed in aporcelain dish and subjected to post-calcination at 330° C. for 0.2 hourin an atmosphere of air, thereby obtaining a catalyst. The compositionof the catalyst and the conditions for the preparation of the catalystare shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

EXAMPLE 9

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example 1except that, before the calcination, the catalyst precursor waspre-calcined at 250° C. for 1 hour in an atmosphere of air. Thecomposition of the catalyst and the conditions for the preparation ofthe catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

EXAMPLE 10

Preparation of an ammoxidation catalyst

An ammoxidation catalyst comprising an compound oxide represented by theformula:

    Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 Zr.sub.0.005 O.sub.n

was prepared as follows.

The preparation of a catalyst was conducted in substantially the samemanner as in Example 1 except that, after the mixing of solutions A andB, to the resultant mixture was added a dispersion obtained bydispersing 0.29 g of zirconyl nitrate [ZrO(NO₃)₂.2H₂ O] in 10.0 g ofwater. The composition of the catalyst and the conditions for thepreparation of the catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

COMPARATIVE EXAMPLE 1

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example 1except that 0.61 g of oxalic acid (H₂ C₂ O₄.2H₂ O) was used (instead of8.27 g). In the obtained solution B, the [H₂ C₂ O₄ :Nb] molar ratio was0.2. The composition of the catalyst and the conditions for thepreparation of the catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained XRDpattern is shown in FIG. 4, and the intensity ratio R is shown in Table1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

COMPARATIVE EXAMPLE 2

Preparation of an ammoxidation catalyst

An ammoxidation catalyst comprising a compound oxide represented by theformula:

    Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n

was prepared as follows.

39.0 g of ammonium heptamolybdate [(NH₄)₆ Mo₇ O₂₄.4H₂ O], 8.53 g ofammonium metavanadate (NH₄ VO₃) and 11.16 g of telluric acid (H₆ TeO₆)were dissolved in 160 g of water at a temperature of 60° C. whilestirring, followed by cooling to 30° C., to thereby obtain a solution(solution A).

4.25 g of niobic acid (Nb₂ O₅.nH₂ O) (Nb₂ O₅ content: 76.0% by weight)and 22.9 g of oxalic acid (H₂ C₂ O₄.2H₂ O) were dissolved in 50 g ofwater at a temperature of 60° C. while stirring, followed by cooling to30° C., to thereby obtain a solution (solution B). In the obtainedsolution B, the [H₂ C₂ O₄ :Nb] molar ratio was 7.5.

Solution B obtained above was added to solution A obtained above and theresultant mixture was stirred for about 30 minutes to obtain a rawmaterial mixture.

The obtained raw material mixture was subjected to spray drying byspraying it onto a Teflon-coated iron plate heated to a temperature of140° C., thereby obtaining a dried particulate catalyst precursor.

Then, 10 g of the obtained catalyst precursor was calcined insubstantially the same manner as in Example 1, to thereby obtain acatalyst. The composition of the catalyst and the conditions for thepreparation of the catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. In the obtained XRDpattern, there was no peak appearing at a diffraction angle (2θ) of27.3±0.3°.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

COMPARATIVE EXAMPLE 3

Preparation of an ammoxidation catalyst

6.0 g of the catalyst precursor obtained in Comparative Example 2 abovewas placed in a porcelain dish and pre-calcined at 250° C. for 2 hoursin an atmosphere of air, thereby obtaining an oxide. 3 g of the obtainedoxide was charged into a quartz tube having an inner diameter of 20 mm,and then calcined at 600° C. for 2 hours under a stream of nitrogen gasat a flow rate of 350 Ncc/min., to thereby obtain a catalyst. Thecomposition of the catalyst and the conditions for the preparation ofthe catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

COMPARATIVE EXAMPLE 4

Preparation of an ammoxidation catalyst

An ammoxidation catalyst comprising a compound oxide represented by theformula:

    Mo.sub.0.1 V.sub.0.33 Nb.sub.0.11 Te.sub.0.40 O.sub.n

was prepared as follows.

39.0 g of ammonium heptamolybdate [(NH₄)₆ Mo₇ O₂₄.4H₂ O], 8.53 g ofammonium metavanadate (NH₄ VO₃) and 20.30 g of telluric acid (H₆ TeO₆)were dissolved in 160 g of water at a temperature of 60° C. whilestirring, followed by cooling to 30° C., to thereby obtain a solution(solution A).

4.25 g of niobic acid (Nb₂ O₅.nH₂ O) (Nb₂ O₅ content: 76.0% by weight)and 22.9 g of oxalic acid (H₂ C₂ O₄.2H₂ O) were dissolved in 50 g ofwater at a temperature of 60° C. while stirring, to thereby obtain asolution (solution B). In the obtained solution B, the [H₂ C₂ O₄ :Nb]molar ratio was 7.5.

Solution B obtained above was added to solution A obtained above and theresultant mixture was stirred for about 30 minutes to obtain a rawmaterial mixture.

The obtained raw material mixture was subjected to spray drying byspraying it onto a Teflon-coated iron plate heated to a temperature of140° C., thereby obtaining a dried particulate catalyst precursor.

6.0 g of the catalyst precursor obtained was placed in a porcelain dishand pre-calcined at 250° C. for 2 hours in an atmosphere of air, therebyobtaining an oxide. 3 g of the obtained oxide was charged into a quartztube having an inner diameter of 20 mm, and then calcined at 600° C. for2 hours under a stream of nitrogen gas at a flow rate of 300 Ncc/min.,to thereby obtain a catalyst. The composition of the catalyst and theconditions for the preparation of the catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained XRDpattern is shown in FIG. 5, and the intensity ratio R is shown in Table1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

COMPARATIVE EXAMPLE 5

Preparation of an ammoxidation catalyst

5.0 g of the catalyst precursor obtained in Example 1 above was placedin a porcelain dish and pre-calcined at 380° C. for 1 hour in anatmosphere of air, thereby obtaining an oxide. 2 g of the obtained oxidewas charged into a quartz tube having an inner diameter of 20 mm, andthen calcined at 600° C. for 2 hours under a stream of nitrogen gas at aflow rate of 200 Ncc/min., to thereby obtain a catalyst. The compositionof the catalyst and the conditions for the preparation of the catalystare shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained XRDpattern is shown in FIG. 6, and the intensity ratio R is shown in Table1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

COMPARATIVE EXAMPLE 6

Preparation of an ammoxidation catalyst

5.0 g of the catalyst precursor obtained in Example 1 above was placedin a porcelain dish and pre-calcined at 360° C. for 2 hours in anatmosphere of air, thereby obtaining an oxide. 2 g of the obtained oxidewas charged into a quartz tube having an inner diameter of 20 mm, andthen calcined at 600° C. for 2 hours under a stream of nitrogen gas at aflow rate of 200 Ncc/min., to thereby obtain a catalyst. The compositionof the catalyst and the conditions for the preparation of the catalystare shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

COMPARATIVE EXAMPLE 7

Preparation of an ammoxidation catalyst

1.0 g of the catalyst obtained in Example 1 above was placed in aporcelain dish and subjected to post-calcination at 450° C. for 2 hoursin an atmosphere of air, thereby obtaining a catalyst. The compositionof the catalyst and the conditions for the preparation of the catalystare shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

COMPARATIVE EXAMPLE 8

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example 1except that the calcination was conducted for 6 hours (instead of 2hours). The composition of the catalyst and the conditions for thepreparation of the catalyst are shown in Table 1.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 1.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 1 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 3.

EXAMPLE 11

Preparation of an ammoxidation catalyst

An ammoxidation catalyst comprising a silica carrier having supportedthereon a compound oxide, wherein the silica carrier is present in anamount of 30% by weight, based on the total weight of the compound oxideand the silica carrier, and wherein the compound oxide is represented bythe formula:

    Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n,

was prepared as follows.

164.31 g of ammonium heptamolybdate [(NH₄)₆ Mo₇ O₂₄.4H₂ O], 36.05 g ofammonium metavanadate (NH₄ VO₃) and 47.15 g of telluric acid (H₆ TeO₆)were dissolved in 720 g of water at a temperature of 60° C. whilestirring, to thereby obtain a solution (solution A).

17.64 g of niobic acid (Nb₂ O₅.nH₂ O) (Nb₂ O₅ content: 76.6% by weight)and 38.45 g of oxalic acid (H₂ C₂ O₄.2H₂ O) were dissolved in 170 g ofwater at a temperature of 60° C. while stirring, followed by cooling to30° C., to thereby obtain a solution (solution B). In the obtainedsolution B, the [H₂ C₂ O₄ :Nb] molar ratio was 3.0.

To solution A obtained above was added 300 g of a silica sol having anSiO₂ content of 30 wt % while stirring, and the resultant mixture wasthen cooled to 30° C., followed by addition of solution B obtainedabove, to thereby obtain a raw material mixture.

The obtained raw material mixture was subjected to spray drying using acentrifugation type spray-drying apparatus under conditions wherein theinlet temperature of the apparatus was 240° C. and the outlettemperature of the apparatus was 145° C., to obtain a dried particulatecatalyst precursor.

The obtained catalyst precursor was pre-calcined at 275° C. for 2 hoursin an atmosphere of air, to obtain an oxide. 80 g of the obtained oxidewas charged into a stainless steel tube having an inner diameter of 1inch, and then calcined at a temperature of 600° C. for 2 hours under astream of nitrogen gas at a flow rate of 150 Ncc/min, to thereby obtaina catalyst. The composition of the catalyst and the conditions for thepreparation of the catalyst are shown in Table 2.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained XRDpattern is shown in FIG. 7, and the intensity ratio R is shown in Table2.

Ammoxidation of propane

Using the catalyst obtained above, an ammoxidation of propane wasconducted as follows.

45 g of the obtained catalyst was charged into a Vycor glassfluidized-bed reactor having an inner diameter of 25 mm. In the reactorcontaining the catalyst, an ammoxidation of propane was performed underconditions wherein the flow rate of a gaseous feedstock mixture (i.e., agaseous mixture of propane, ammonia, molecular oxygen and helium) was350 Ncc/min, the [propane:ammonia:molecular oxygen:helium] molar ratioin the gaseous feedstock mixture was 1.0:1.2:3.0:12.0, the ammoxidationtemperature was 430° C., the ammoxidation pressure was 1 atm., and thecontact time between the catalyst and the gaseous feedstock mixture was3.0 sec·g/cc. The produced gaseous reaction mixture was subjected toanalysis by means of an on-line chromatography.

The results of the evaluation of the above ammoxidation are shown inTable 4.

EXAMPLE 12

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example11 except that, in the preparation of solution B, 34.60 g of oxalic acid(H₂ C₂ O₄.2H₂ O) was used (instead of 38.45 g). In the obtained solutionB, the [H₂ C₂ O₄ :Nb] molar ratio was 2.7. The composition of thecatalyst and the conditions for the preparation of the catalyst areshown in Table 2.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 2.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 11 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 4.

EXAMPLE 13

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example11 except that, in the preparation of solution B, 44.85 g of oxalic acid(H₂ C₂ O₄.2H₂ O) was used (instead of 38.45 g). In the obtained solutionB, the [H₂ C₂ O₄ :Nb] molar ratio was 3.5. The composition of thecatalyst and the conditions for the preparation of the catalyst areshown in Table 2.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 2.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 11 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 4.

EXAMPLE 14

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example11 except that, in the preparation of solution B, 160 g of water wasused (instead of 170 g) and 6.9 g of 25 wt % aqueous ammonia was added.In the obtained solution B, the [H₂ C₂ O₄ :Nb] molar ratio was 3.0 andthe [ammonia:Nb] molar ratio was 1.0. The composition of the catalystand the conditions for the preparation of the catalyst are shown inTable 2.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 2.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 11 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 4.

COMPARATIVE EXAMPLE 9

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example11 except that, in the preparation of solution B, 150 g of water wasused (instead of 170 g) and 16.6 g of 25 wt % aqueous ammonia was added.In the obtained solution B, the [H₂ C₂ O₄ :Nb] molar ratio was 3.0 andthe [ammonia:Nb] molar ratio was 2.4. The composition of the catalystand the conditions for the preparation of the catalyst are shown inTable 2.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 2.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 11 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 4.

COMPARATIVE EXAMPLE 10

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example11 except that, in the preparation of solution B, 96.11 g of oxalic acid(H₂ C₂ O₄.2H₂ O) was used (instead of 38.45 g). In the obtained solutionB, the [H₂ C₂ O₄ :Nb] molar ratio was 7.5. The composition of thecatalyst and the conditions for the preparation of the catalyst areshown in Table 2.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 2.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 11 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 4.

COMPARATIVE EXAMPLE 11

Preparation of an ammoxidation catalyst

A catalyst was prepared in substantially the same manner as in Example11 except that, in the preparation of solution B, 3.84 g of oxalic acid(H₂ C₂ O₄.2H₂ O) was used (instead of 38.45 g). In the obtained solutionB, the [H₂ C₂ O₄ :Nb] molar ratio was 0.3. The composition of thecatalyst and the conditions for the preparation of the catalyst areshown in Table 2.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained intensityratio R is shown in Table 2.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 11 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 4.

COMPARATIVE EXAMPLE 12

Preparation of an ammoxidation catalyst

45.0 g of the catalyst obtained in Example 11 above was placed in aporcelain dish and subjected to post-calcination at 450° C. for 2 hoursin an atmosphere of air, thereby obtaining a catalyst. The compositionof the catalyst and the conditions for the preparation of the catalystare shown in Table 2.

X-ray diffractometry

With respect to the catalyst obtained above, substantially the same XRDpattern measurement as in Example 1 was repeated. The obtained XRDpattern is shown in FIG. 8, and the intensity ratio R is shown in Table2.

Ammoxidation of propane

Using the catalyst obtained above, substantially the same ammoxidationof propane as in Example 11 was repeated. The results of the evaluationof the above ammoxidation are shown in Table 4.

                                      TABLE 1                                     __________________________________________________________________________                               Pre-              Re-    Post-                                       Molar    calcination                                                                          Calcination                                                                              calcination                                                                          calcination                                                                          Inten-             Composition of    ratio to Nb.sup.1)                                                                     Temp.                                                                             Time                                                                             Temp.                                                                             Time                                                                             Grind-                                                                            Temp.                                                                             Time                                                                             Temp.                                                                             Time                                                                             sity               ammoxidation catalyst                                                                           H.sub.2 C.sub.2 O.sub.4                                                           Ammonia                                                                            (° C.)                                                                     (hr)                                                                             (° C.)                                                                     (hr)                                                                             ing (° C.)                                                                     (hr)                                                                             (° C.)                                                                     (hr)                                                                             ratio              __________________________________________________________________________                                                               R.sup.2)           Ex. 1                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    --  -- 600 2  no  --  -- --  -- 0.46               Ex. 2                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    --  -- 600 2  no  550 2  --  -- 0.47               Ex. 3                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    --  -- 600 2  40 min.                                                                           550 2  --  -- 0.56               Ex. 4                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    --  -- 600 2  40 min.                                                                           550 1  --  -- 0.55               Ex. 5                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.8 0    --  -- 600 2  no  --  -- --  -- 0.45               Ex. 6                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       3.0 0    --  -- 600 2  no  --  -- --  -- 0.46               Ex. 7                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       3.0 0    --  -- 600 2  no  --  -- 320 0.3                                                                              0.48               Ex. 8                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       3.0 0    --  -- 600 2  no  --  -- 330 0.2                                                                              0.48               Ex. 9                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    250 1  600 2  no  --  -- --  -- 0.45               Ex. 10                                                                            Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 Zr.sub.0.005 O.sub.n                          2.7 0    --  -- 600 2  no  --  -- --  -- 0.49               Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       0.2 0    --  -- 600 2  no  --  -- --  -- 0.01               Ex. 1                                                                         Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       7.5 0    --  -- 600 2  no  --  -- --  -- 0                  Ex. 2                                                                         Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       7.5 0    250 2  600 2  no  --  -- --  -- 0.20               Ex. 3                                                                         Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.40 O.sub.n                                       7.5 0    250 2  600 2  no  --  -- --  -- 0.02               Ex. 4                                                                         Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    380 1  600 2  no  --  -- --  -- 0.32               Ex. 5                                                                         Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    360 2  600 2  no  --  -- --  -- 0.18               Ex. 6                                                                         Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    --  -- 600 2  no  --  -- 450 2  0.88               Ex. 7                                                                         Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n                                       2.7 0    --  -- 600 6  no  --  -- --  -- 0.82               Ex. 8                                                                         __________________________________________________________________________     Note .sup.1) : Molar ratio of oxalic acid (H.sub.2 C.sub.2 O.sub.4) to        niobium (Nb); and molar ratio of ammonia to niobium (Nb).                     Note .sup.2) : Intensity ratio R means the intensity ratio defined by the     formula: R = P.sub.1 /(P.sub.1 + P.sub.2) wherein P.sub.1 and P.sub.2         represent the intensities of peaks 1 and 2 appearing at diffraction angle     (2θ) of 27.3° + 0.3° and 28.2° ±                0.3°, respectively.                                               

                                      TABLE 2                                     __________________________________________________________________________                               Pre-              Re-    Post-                                       Molar    calcination                                                                          Calcination                                                                              calcination                                                                          calcination                                                                          Inten-             Composition of    ratio to Nb.sup.1)                                                                     Temp.                                                                             Time                                                                             Temp.                                                                             Time                                                                             Grind-                                                                            Temp.                                                                             Time                                                                             Temp.                                                                             Time                                                                             sity               ammoxidation catalyst.sup.3)                                                                    H.sub.2 C.sub.2 O.sub.4                                                           Ammonia                                                                            (° C.)                                                                     (hr)                                                                             (° C.)                                                                     (hr)                                                                             ing (° C.)                                                                     (hr)                                                                             (° C.)                                                                     (hr)                                                                             ratio              __________________________________________________________________________                                                               R.sup.2)           Ex. 11                                                                            Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             3.0 0    275 2  600 2  no  --  -- --  -- 0.69               Ex. 11                                                                            Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             3.0 0    275 2  600 2  no  --  -- --  -- 0.69               Ex. 12                                                                            Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             2.7 0    275 2  600 2  no  --  -- --  -- 0.49               Ex. 13                                                                            Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             3.5 0    275 2  600 2  no  --  -- --  -- 0.64               Ex. 14                                                                            Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             3.0 1.0  275 2  600 2  no  --  -- --  -- 0.55               Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             3.0 2.4  275 2  600 2  no  --  -- --  -- 0.16               Ex. 9                                                                         Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             7.5 0    275 2  600 2  no  --  -- --  -- 0.32               Ex. 10                                                                        Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             0.3 0    275 2  600 2  no  --  -- --  -- 0.02               Ex. 11                                                                        Comp.                                                                             Mo.sub.1.0 V.sub.0.33 Nb.sub.0.11 Te.sub.0.22 O.sub.n SiO.sub.2                             3.0 0    275 2  600 2  no  --  -- 450 2  0.87               Ex. 12                                                                        __________________________________________________________________________     Note .sup.1) : Molar ratio of oxalic acid (H.sub.2 C.sub.2 O.sub.4) to        niobium (Nb); and molar ratio of ammonia to niobium (Nb).                     Note .sup.2) : Intensity ratio R means the intensity ratio defined by the     formula: R = P.sub.1 /(P.sub.1 + P.sub.2) wherein P.sub.1 and P.sub.2         represent the intensities of peaks 1 and 2 appearing at diffraction angle     (2θ) of 27.3° + 0.3° and 28.2° ±                0.3°, respectively.                                                    Note .sup.3) : In Examples 11 to 14 and Comparative Examples 9 to 12, the     amount of the silica carrier (SiO.sub.2) is 30 wt %.                     

                                      TABLE 3                                     __________________________________________________________________________           Ammoxidation conditions                                                                            Evaluation of ammoxidation                               [propane:            Ammonia                                                  ammonia:molecular                                                                      Reaction                                                                            Contact                                                                             decomposition                                                                        Conversion                                                                          Selectivity of                                                                      Yield of                              oxygen:helium]                                                                         temperature                                                                         time  ratio  of propane                                                                          acrylonitrile                                                                       acrylonitrile                         molar ratio                                                                            (° C.)                                                                       (sec · g/cc)                                                               (%)    (%)   (%)   (%)                            __________________________________________________________________________    Ex. 1  1.0/1.2/3.0/14.8                                                                       420   1.2   32.1   90.8  61.8  56.1                           Ex. 2  1.0/1.2/3.0/14.8                                                                       420   1.2   32.8   91.5  61.3  56.1                           Ex. 3  1.0/1.2/3.0/14.8                                                                       420   0.5   30.5   92.9  63.5  58.9                           Ex. 4  1.0/1.2/3.0/14.8                                                                       420   0.5   29.4   93.1  63.3  58.9                           Ex. 5  1.0/1.2/3.0/14.8                                                                       420   1.2   31.0   90.4  61.2  55.4                           Ex. 6  1.0/1.2/3.0/14.8                                                                       420   1.2   33.1   89.7  60.2  54.0                           Ex. 7  1.0/1.2/3.0/14.8                                                                       420   1.2   32.2   90.5  61.2  55.4                           Ex. 8  1.0/1.2/3.0/14.8                                                                       420   1.2   31.8   90.6  61.6  55.6                           Ex. 9  1.0/1.2/3.0/14.8                                                                       420   1.2   33.1   89.2  61.9  55.2                           Ex. 10 1.0/1.2/3.0/14.8                                                                       420   1.2   30.7   90.6  61.7  55.9                           Comp. Ex. 1                                                                          1.0/1.2/3.0/14.8                                                                       420   1.2   96.6   1.4   37.1  0.5                            Comp. Ex. 2                                                                          1.0/1.2/3.0/14.8                                                                       420   1.2   93.3   10.3  40.9  4.2                            Comp. Ex. 3                                                                          1.0/1.2/3.0/14.8                                                                       420   1.2   61.2   66.1  66.2  43.4                           Comp. Ex. 4                                                                          1.0/1.2/3.0/14.8                                                                       420   1.2   97.5   7.4   36.9  2.7                            Comp. Ex. 5                                                                          1.0/1.2/3.0/14.8                                                                       420   1.2   40.0   86.5  59.7  51.6                           Comp. Ex. 6                                                                          1.0/1.2/3.0/14.8                                                                       420   1.2   59.7   41.7  58.9  24.6                           Comp. Ex. 7                                                                          1.0/1.2/3.0/14.8                                                                       420   1.2   80.4   35.5  59.3  21.0                           Comp. Ex. 8                                                                          1.0/1.2/3.0/14.8                                                                       420   1.2   79.1   30.5  63.9  19.5                           __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________           Ammoxidation conditions                                                                            Evaluation of ammoxidation                               [propane:            Ammonia                                                  ammonia:molecular                                                                      Reaction                                                                            Contact                                                                             decomposition                                                                        Conversion                                                                          Selectivity of                                                                      Yield of                              oxygen:helium]                                                                         temperature                                                                         time  ratio  of propane                                                                          acrylonitrile                                                                       acrylonitrile                         molar ratio                                                                            (° C.)                                                                       (sec · g/cc)                                                               (%)    (%)   (%)   (%)                            __________________________________________________________________________    Ex. 11 1.0/1.2/3.0/12.0                                                                       430   3.0   31.6   85.2  60.9  51.9                           Ex. 12 1.0/1.2/3.0/12.0                                                                       430   3.0   31.4   84.0  57.0  47.9                           Ex. 13 1.0/1.2/3.0/12.0                                                                       430   3.0   31.3   84.9  60.1  51.0                           Ex. 14 1.0/1.2/3.0/12.0                                                                       430   3.0   31.5   85.0  59.0  50.2                           Comp. Ex. 9                                                                          1.0/1.2/3.0/12.0                                                                       430   3.0   61.2   72.8  46.6  33.9                           Comp. Ex. 10                                                                         1.0/1.2/3.0/12.0                                                                       430   3.0   47.7   74.1  52.8  39.1                           Comp. Ex. 11                                                                         1.0/1.2/3.0/12.0                                                                       430   3.0   95.8   1.2   31.2  0.4                            Comp. Ex. 12                                                                         1.0/1.2/3.0/12.0                                                                       430   3.0   63.5   44.1  56.7  25.0                           __________________________________________________________________________

INDUSTRIAL APPLICABILITY

By the use of the ammoxidation catalyst of the present invention inproducing acrylonitrile or methacrylonitrile from propane or isobutane,not only can acrylonitrile or methacrylonitrile be produced in highyield, but also oxidative decomposition of ammonia feedstock intonitrogen can be effectively suppressed, thereby enabling an improvedutilization of ammonia as a feedstock.

What is claimed is:
 1. An ammoxidation catalyst for use in producingacrylonitrile or methacrylonitrile from propane or isobutane byammoxidation in the gaseous phase, comprising a compound oxiderepresented by the following formula (1):

    Mo.sub.1.0 V.sub.p X.sub.q Nb.sub.r Z.sub.s O.sub.n        ( 1)

wherein: X is at least one element selected from the group consisting oftellurium and antimony; Z is at least one element selected from thegroup consisting of tantalum, tungsten, chromium, titanium, zirconium,bismuth, tin, hafnium, manganese, rhenium, iron, ruthenium, cobalt,rhodium, nickel, palladium, platinum, silver, zinc, boron, aluminum,gallium, indium, germanium, lead, phosphorus, rare earth elements andalkaline earth metals, and p, q, r, s and n are, respectively, theatomic ratios of vanadium, X, niobium, Z and oxygen, relative tomolybdenum,wherein

    0.1≦p≦0.6;

    0.01≦q≦0.6;

    0.01≦r≦0.6;

    0≦s≦1;

and n is a number determined by the valence requirements of the otherelements present, said compound oxide exhibiting an X-ray diffractionpattern satisfying the following relationship (2):

    0.40≦R≦0.75                                  (2)

wherein R represents the intensity ratio defined by the followingformula (3):

    R=P.sub.1 /(P.sub.1 +P.sub.2)                              (3)

wherein P₁ and P₂ represent the intensities of peak 1 and peak 2appearing at diffraction angles (2θ) of 27.3±0.3° and 28.2±0.3°,respectively.
 2. The catalyst according to claim 1, wherein R inrelationship (2) satisfies the following relationship:

    0.43≦R≦0.70.


3. 3. The catalyst according to claim 2, which further comprises asilica carrier having supported thereon said compound oxide, whereinsaid silica carrier is present in an amount of from 20 to 60% by weight,based on the total weight of said compound oxide and said silicacarrier.
 4. The catalyst according to claim 1, which further comprises asilica carrier having supported thereon said compound oxide, whereinsaid silica carrier is present in an amount of from 20 to 60% by weight,based on the total weight of said compound oxide and said silicacarrier.